Furnace for limekilns or other structures.



No'. 793,392. l PATENTBD JUNE 27, 19o5 J. D. OWENS.

FURNA-CE POR LIMEKILNS 0R OTHER STRUCTURES.

APPLIoATIoN FILED Aun. 15,1903.

wilnaoaeo j@ APPLICATION FILED APR. 15,1903.

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M I aufn-nua NTTED STATES Patented June 2'7, 1905.

PATENT OEEICE.

FURNACE FOR LIMEKILNS OR OTHER STRUCTURES.

SPECIFICATION forming part of Letters Patent No. 793,392, dated June 27, 1905.

Application filed April 15, 1903. Serial No. 152.661.

To all whim/1, it may concern.'

Be it known that I, JOHN D. OWENS, a citizen of the United States, residing at Marion, in the county of Marion and State of Ohio,have invented certain new and useful Improvements in Furnaces for Limekilns or other Structures,

lof which the following is aspecilication, reference being had therein to the accompanying drawings.

duced of a character such that too. great a temperature will not result at the eye of the furnace.

To these ends the invention consists in certain novel features, which I will now proceed to describe and will then particularly point out in the claims.

1n the accompanying drawings, Figure 1 is a vertical sectional view of a limekiln embodying my invention, the same being in section on the line a a' of Fig. 2 and looking in the direction of the arrows. Fig. 2 is a plan section taken on the line y y of Fig. l and looking in the direction of the arrows, and Fig. 3 is a vertical section taken on the line .e of Fig. 2 and looking in the direction of the arrows.

Heretofore lime has been burned in kilns consisting of a main chamber, in which the lime to be burned is charged, having a door near the bottom for the withdrawal of the burned lime and furnaces located a suitable distance above the bottom of the kiln and communicating with the chamber thereof by eyes, so as to cause the products of combustion to cnter'said main chamber some distance above the bottom. These furnaces as ordinarily constructed consist of a chamber divided by grate-bars into an upper and a lower section,

the upper section constituting the combustion-chamber and the lower section the ashpit. The entire chamber is located above the ioor-line or ground-line adjacent to the kiln, and each section of the chamber has a door or closure, fuel being charged in through the temperature and length of the flame produced by its combustion. It is necessary that the heat should not be too great Where the iiame enters the main chamber of the kiln through the eye of the furnace to prevent overburning of the lime at that point, and it is also necessary that the Hame should extend upward through the material in the kiln a distance sufficient to thoroughly burn the stone without overburning it to a height above the fire-line suflicient to fill the part of the kiln below the fire-line. In this way when a charge is withdrawn from the lower partof the kiln the stone which descends to fill said space will all be properly burned, and after supporting the superincumbent mass while it is being burned to theproper degree may be then withdrawn. Owing to the scarcity of wood as fuel, a substitute therefor has been sought and attempts have been made to burn soft or bituminous coal in the ordinary kilnfurnace. The results, however, have been unsatisfactory, because if the temperature is sufciently high to cause a flame long enough to reach to the desired height within thekiln the temperature is too high at the eye of the furnace and the lime at that point is overburned. In fact, the temperature may be such as to burn the stone too hard at the eye without burning it to a sufficient extent above the eye. Thereforeaportion of the charge would be overburned and another portion of the charge sometimes not sufiiciently burned. A further disadvantage of this coal is that a large portion of it forms into coke upon the gratebars and no longer gives the desired flame, so

fall lthrough unconsumed.

that it must be withdrawn unconsumed from thelfurnace and its place supplied with fresh fue In the accompanyingdrawings I have shown one form of apparatus adapted for use in carrying out my invention.

In said drawings,1 indicates the body of the kiln,and 2 the main chamber thereof, in which the limestone is charged. y y

3 indicates the iioor or ground line, and 11 an opening near the bottom of the kiln, through which the burned Charges are withdrawn. The base of the kiln has a recess 5 formed in it (indicated in dotted lines in Fig. 2) to give access to the opening 4.

The furnaces, as usual, are in duplicate and each consists of a combustion-cham ber 6, having at one end a feed-door 7 and at the other end an eye 8, opening into the chamber 2. 'Ihe bottom ofthe main portion of the combustion -chamber is formed of gratebars 9, located a suflicient distance apart to give an adequate air-supply to the bed of fuel resting on them and to permit particles of the fuel to In practice I have found that an opening of one inch between vthe grate-bars at the top thereof is suilicient for this purpose, the openings increasing downwardly in width to prevent clogging. A flue or passage 10 extends downward from the combustion-chamber into the base of thekiln, and one of the walls of said iiue or passage, preferably that nearest the chamber 2, is inclined on a gradual slope downward and outward, as indicated at 11, and its surface is roughened or formed with projections to retain thc fuel thereon. municates at its lower end with a chamber 12, located at a considerable distance below the main combustion-chamber and having a floor 'or bottom 13, on which the dropping fuel accumulates. The iioor or bottom 13 is imperforate or closed, so that the air-supply passes over and not through the fuel lying thereon,

and the combustion-chamber 18 is located lat` eral ly with respect to the combustion-'chamber 6, so as to give the necessary extent and slope to the wall 11 of the flue or passage 1() to permit the formation thereon of an extended inclined fuel-bed, the said iue or passage 10 being so constructed as to cause the commingled gas and products of partial combustion arising from the chamber 12 to pass over said inclined bed of fuel. A passage 14 (indicated in dotted lines in Fig. 2) leads from the chamber 12 to the atmosphere, preferably at the front of the kiln. Valves 15, mounted on rock-shafts 16 in each passage 10 immediately below the grate-bars, serve to regulate the supply of air and gases tothe main combustion-chamber, and provision may be made by means of sliding doors 17 for the regulation of the admission of air to the passages 111. It will be noted that thevalves l5 are so arranged Each passage 10 com-v that,while they control the supply of air and gases to the main combustion-chamber, they insure the equal distribution of said supply throughout the entire length of said main combustion-chamber.

The apparatus being thus constructed, the operation is begun by the lighting of a comparatively thin bed of soft coal on the gratebars 9. A portion of this fuel falls through between the grate-bars in a partially-consumed and still-burning condition, and these particles fall upon the inclined wall 11, some of them lodging there, while others pass down into the chamber 12 and accumulate on the iioor 13 thereof. tial combustion of the fuel upon the floor 13 is maintained, so as to form an auxiliary bed of fuel below the main bed, and a similar bed of 'smoldering fuel is `maintained along the inclined wall 11. umes through the passage 14 and maintains the desired Acombustion at the lower fuel-bed, over which it passes, carrying .up along with it the gases produced by said partial combustion. Other gases are gathered from the inclined fuel-bed 11 in the iiue or passage 10, and as said ilue or passage is maintained at a relatively high temperature the mixture of air and gases reaches the main fuel-bed in a highly-heated condition and can be seen jetting up through the samein vigorous combustion. rIhis resultsin the production of a long flame extending upward in the interior of the main chamber of the kiln to the desired distance and having a temperature such as to properly burn the stone therein without overburning. The fuel in the main combustionchamber is practically all consumed except that portion thereof which falls through the grate-bars, and said fuel does not coke upon the bars and have to be removed. If the dropping particles accumulate too rapidly in the lower combustion-chamber, they may be either recharged in the main combustionchamber or burned elsewhere.

In practice I have found that by the use of this structure a material saving in cost of production may be made both over the old wood process and the old coal process. There is also a material gain over the old structure in that none of the stone is overburned or underburned. It is also possible by my improved structure to materially increase the output, if necessary, by forcing the kiln without damaging the product.

It is obvious that the furnace above described may be utilized for other purposes than the burning of lime, it being adapted for use wherever a llame of the character produced thereby is required. I

I make no claim in this application to the process hereinbefore described, as the same 'forms the subject-matter of a separate application filed of even date herewith.

A slow smoldering or par-` rIhe air enters in large vol- IOO IIO

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

l. In a soft-coal furnace for limekilns, an upper main combustionlchamber, having a dame-outlet and a charging-door, the floor of said chamber being formed of grate bars spaced as described, a lower auxiliary combustion-chamber having' an imperforate ioor to support the partly-burned fuel falling from the upper chamber, said auxiliary chamber being laterally offset with respect to the upper combustion-chamber, so asto be outside the downward extension of its lateral boundaries, a passage extending upward from the lower chamber to the lower end of the upper chamber, said passage having an inclined or sloping wall extending under the entire gratesurface of the upper chamber and constructed and arranged to maintain thereon aninclined bed of fuel formed by the droppings from the upper chamber, and an air-supply conduit arranged to conduct air from the exterior over the fuel in the lower chamber to theupwardlyextending passage, said air-supply conduit constituting the sole source of supply of air to the fuel, and said upwardly-extending passage conducting the air and gases from the lower chamber over the inclined bed of fuel and delivering all of the resulting mixture below the grate of the upper chamber, substantially as described.

2. In a soft-coal furnace for limckilns andA other structures, an upper main combustionchamber havlng a Haine-outlet and a chargmgdoor, the floor of said chamber being formed to conduct the air from the exterior over the fuel in the lower chamber to the upwardlyextending passage, whereby said upwardlyextending passage conducts the air and the gases from the lower chamber to the under side of the grate ofthe upper chamber and constitutes the air-supplying means for the upper chamber, and means located within said passage below the grate for controlling the amount and equalizing the delivery to the grate of the air andv partially-consumed gases, substantially as described.

3. In a soft-coal furnace for limelzilns and other structures, an upper main combustionchamber having a flame-outlet and a chargingdoor, the floor of said chamber being formed of grate-bars spaced as described, va lower auxiliary combustion-chamber having an imperforate fioor to' 'receive the partly-burned fuel falling from the upper chamber, a passage extending upward from the lower chamber to a point below the grate of the upper chamber, an air-supply conduit arranged to conduct the air from the exterior over the fuel in the lower chamber to the upwardlyextending passage, whereby said upwardlyextending passage conducts the air and gases from the lower chamber to the under side of the grate of the upper chamber and constitutes the air-supplying means for the upper chamber, means located within said upwardlyi 

